CD3+ICOS+ T cells show differences in the synthesis of nitric oxide, IFN-γ, and IL-10 in patients with pulmonary tuberculosis or in healthy household contacts.

Evidence indicates that more than 90 % of infected individuals never develop active tuberculosis. This fact highlights the relevance of the immune response in tuberculosis control. The inducible co-stimulator (ICOS) is a regulator of the function, differentiation, proliferation, and activation of T cells. Moreover, T cells synthesise nitric oxide (NO), interferon gamma (IFN-γ), and interleukin (IL)-10, which help regulate the immune response to tuberculosis. Therefore, we assessed the synthesis of NO, IFN-γ, and IL-10 in CD3+ICOS+ T cells from healthy individuals, household contacts (HHC), and patients with active pulmonary tuberculosis (PTB), previously stimulated with the antigen H37Rv. Our results indicated a significant increase in both the percentage of ICOS+ cells and CD3+ICOS+ T cells producing NO, IFN-γ, and IL-10 in cells obtained from patients with PTB (p < 0.01). In addition, a high mitochondrial membrane potential (ΔΨ m) in CD3+ICOS+ T cells was observed in the cells from HHC and from PTB patients, and is associated with the activation of T cells. In conclusion, results show that the CD3+ICOS+ T cells obtained from PTB patients are the main producers of NO, IFN-γ, and IL-10. In addition, our results imply that NO is a modulator of ICOS expression of T cells from PTB patients.